Time Independent Functional Training of Inter-joint Arm Coordination Using the ARMin III Robot

Abstract

Task specific training is a cornerstone of stroke motor therapy and is thought to contribute to improvement of function in activities of daily living (ADLs). Abnormal synergies after stroke often make the training of proper inter-joint coordination during functional tasks difficult, since patients are inclined to utilize abnormal compensatory movement patterns. Effective inter-joint coordination training may be important for regaining functional use of the limb. We have developed a novel robotic method for retraining inter-joint coordination based on time independent joint based control. An integral component of this method is facilitation of proper patient interaction with the robot, which is essential to maximize gains. While robots can assist completion of movement, patient control of the movement is frequently minimal, leading to little or no effort by the patient during training. To increase patient engagement, we have incorporated feed-forward friction compensation to improve backdriveability, gravity compensation for both the robot and human arms, and a visual interface to improve patient interactions with the robot.